JP2008239739A - Thermoplastic resin film and production method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin film having excellent heat-resistance, optical isotropy and transparency, and excellent in treatability and processibility, to provide an optical film excellent in treatability while realizing excellent transparency, especially a thermoplastic resin film suitable as a polarizer protecting film, by having on at least one side of the resin film, functional layers such as a hard coat layer, an antistatic layer, a UV absorbing layer, an adhesive layer and an antireflection layer. <P>SOLUTION: The thermoplastic resin film comprises a thermoplastic resin having ≥110°C glass transition temperature, and has ≥1.6% total haze, ≤1.0% internal haze, ≤10 nm in-plane retardation Δnd, and from -10 nm to 10 nm thickness direction retardation Rth. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a new and industrially useful thermoplastic resin film having excellent heat resistance and optical isotropy, and excellent handleability, and a method for producing the same.

  More specifically, for example, it is useful as a surface protection material for display materials such as flat display panels, interior materials and exterior materials for vehicles, electrical appliances, inner layers and exterior materials for building materials, and various films used for them. In particular, the present invention relates to a thermoplastic resin useful as a material for a flat display panel such as a polarizer protective film and a method for producing the same because of its excellent heat resistance and optical isotropy.

  Various polymer resin films, especially acrylic resin, polycarbonate, vinyl chloride, cyclic olefin, and other films are excellent in transparency and surface glossiness, so liquid crystal display sheets or films, optical materials such as light guide plates, and vehicles Used in a wide range of fields such as interior materials and exterior materials, exterior materials for vending machines, electrical appliances, inner layers for building materials and surface skins of exterior materials.

  With regard to these resin films, particularly liquid crystal display sheets or films, for example, with the increase in brightness and definition of liquid crystal televisions, higher heat resistance and smaller in-plane and thickness direction retardation are obtained. There is a demand for a film having excellent isotropy. In order to cope with these, acrylic resin films (Patent Documents 1 to 3) having a glutaric anhydride unit represented by the following structural formula (1) and alicyclic polyolefin resin films having a norbornene structure (Patent Document 4) Or a polarizer protective film (Patent Document 5) using a resin containing a soft acrylic resin, an acrylic rubber, or a rubber-acrylic graft-type shell core polymer in an acrylic resin.

(In the above formula, R ¹ and R ² represent the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.)
However, in order to cope with the rapid screen enlargement and price reduction in recent years, the film width and the processing line speed have been increased. As a result, the film can be conveyed, wound, and fine scratches on the surface can be generated. Due to charging at the time of unwinding, transportability and charging, problems in the production process such as generating defects when forming a hard coat layer or antireflection film, etc. have become obvious, and manufacturing costs can be reduced. It is an obstacle.
JP 2005-314534 A JP 2006-206881 A JP 2006-241263 A JP 2006-62109 A JP 2006-284882 A

  An object of the present invention is to provide a thermoplastic resin film that is excellent in heat resistance, optical isotropy, and transparency, and excellent in handleability and processability, in view of the problems of the prior art. . In addition, by having functional layers such as a hard coat layer, an antistatic layer, an ultraviolet absorbing layer, an adhesive layer, and an antireflection layer on at least one side of the resin film, it exhibits high transparency and has excellent handling properties. It is providing the thermoplastic resin film suitable as a film for a film, especially a polarizer protective film.

As a result of intensive studies in view of the above-described problems, the present inventors have controlled the total haze and internal haze of the thermoplastic resin to a specific range, and thus have high handleability and workability while being highly processed. The present inventors have found that a thermoplastic resin film that can exhibit transparency and is excellent in heat resistance and optical isotropy can be obtained, and uses the following means. That is, it contains a thermoplastic resin having a glass transition temperature of 110 ° C. or higher, the total haze of the film is 1.6% or higher, the internal haze is 1.0% or lower, the in-plane retardation Δnd is 10 nm or lower, and the thickness direction retardation is Rth is -10 to 10 nm, a thermoplastic resin film.
Moreover, the thermoplastic resin film of the present invention has the following preferred modes (a) to (k).

  (A) The surface haze is 1.0% or more.

  (B) The thermoplastic resin is an acrylic resin.

  (C) The acrylic resin is an acrylic resin (A) containing a glutaric anhydride unit represented by the following structural formula (1).

  (D) The acrylic resin (A) containing the glutaric anhydride unit represented by the structural formula (1) is contained in an amount of 50 to 95% by mass and acrylic elastic particles (B) in an amount of 5 to 50% by mass. As a structural unit of the resin (A), at least methyl methacrylate units 55 to 95 mol% and glutaric anhydride units 5 to 45 mol% are contained, and the sum of methyl methacrylate units and glutaric anhydride units is 90 mol% or more. The thermoplastic resin film as described above.

  (E) The acrylic elastic particles (B) have a particle diameter of 50 to 300 nm.

  (F) The acrylic elastic particle (B) is a rubber elastic body in which the inner layer contains an alkyl acrylate ester unit and / or an aromatic vinyl unit, and the outer layer contains an acrylic resin containing a glutaric anhydride unit. It is a coalescence and the difference in refractive index between the acrylic elastic particles (B) and the acrylic resin (A) is 0.010 or less.

  (G) The light transmittance at 380 nm is 10% or less.

  (H) A single layer structure.

  (I) A hard coat layer is laminated on at least one surface.

  (J) To be used for optical purposes.

  (K) A method for producing a thermoplastic resin film in which a molten thermoplastic resin is extruded from a die onto a cooling roll using an extruder and solidified, and a draft ratio between the die and the cooling roll is 10 or more, and The method for producing a thermoplastic resin film as described above, wherein an average residence time from the extruder outlet to the die outlet of the molten thermoplastic resin is 30 to 60 minutes.

(In the above formula, R ¹ and R ² represent the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.)

  ADVANTAGE OF THE INVENTION According to this invention, the thermoplastic resin film excellent in heat resistance and optical isotropy which can express high transparency after a process, having the outstanding handleability and workability can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described.

  The thermoplastic resin used in the present invention is not particularly limited as long as it is substantially transparent. For example, acrylic resin, polycarbonate, vinyl chloride, and alicyclic polyolefin are preferable. Resins are preferably used.

  The alicyclic polyolefin resin is a polyolefin resin having an alicyclic structure in the main chain and / or side chain, such as a norbornene resin, a monocyclic olefin resin, a cyclic conjugated diene resin, a vinyl alicyclic ring. And hydrocarbon hydrocarbon resins thereof, and hydrides thereof. Among these, norbornene-based resins are particularly preferable because of their good transparency and moldability.

  An acrylic resin is a resin obtained by polymerizing acrylic acid and its derivatives, and in the present invention, it is represented by the following general formula (1) in the molecule for the purpose of exhibiting heat resistance and optical isotropy. It is preferable to contain a glutaric anhydride unit.

(In the above formula, R ¹ and R ² represent the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.)
The heat resistance of the resin film, such as the glass transition temperature (Tg) and the heat distortion temperature, is determined by the degree of freedom of the resin structure. For example, an aromatic material in which a rigid benzene ring is bonded by a rigid imide bond. Polyimide has a Tg of over 400 ° C. On the other hand, Tg of polymethacrylmethyl (PMMA), which is a flexible aliphatic polymer having a high degree of freedom, is less than 100 ° C. The acrylic resin that can be used in the present invention is preferable because it has an alicyclic structure and contains glutaric anhydride units, which can significantly improve heat resistance. In addition, a small phase difference is required for optical isotropic applications. Here, when an aromatic ring having many π electrons is introduced, the heat resistance is improved more than the introduction of an alicyclic structure, but at the same time, there is a problem that birefringence increases and a phase difference is easily developed. For this reason, it is most preferable to contain an alicyclic structure in order to improve heat resistance while maintaining optical isotropy. Examples of the alicyclic structure include a glutaric anhydride structure, a lactone ring structure, a norbornene structure, and a cyclopentane structure. For optical isotropy and heat resistance, the same effect can be obtained using any structure, but for the introduction of lactone ring structure, norbornene structure, cyclopentane structure, etc., use expensive raw materials having these structures, Alternatively, it is industrially disadvantageous because it is necessary to use an expensive raw material to be a precursor of these structures and to achieve a target structure through several steps of reaction. On the other hand, glutaric anhydride units are industrially very advantageous because they are obtained from a general acrylic raw material by a one-step dehydration and / or dealcoholization reaction.

Here, the optical isotropy application is an application in which optical isotropy is required inside the material, and specific examples thereof include a polarizing plate protective film, a lens, and an optical waveguide core. In a liquid crystal television, two polarizing plates are used orthogonally or in parallel, but when a polarizing plate protective film does not exist or is optically isotropic, black is displayed in a state where the two polarizing plates are orthogonal, When two polarizing plates are parallel, white is displayed. On the other hand, when the polarizing plate protective film is not optically isotropic, for example, dark purple is displayed instead of black when the two polarizing plates are orthogonal to each other, and yellow is displayed instead of white when the two polarizing plates are parallel. . This coloring varies depending on the anisotropy of the polarizing plate protective film. Ideally, the polarizing plate protective film does not exist optically, but is essential for the purpose of protecting the polarizer from external stress and moisture. In the case of a lens, the lens is intended to refract light at the interface, but it is necessary for light to travel uniformly within the lens. If the inside of the lens is not optically isotropic, there is a problem that the image is distorted. In the case of the optical waveguide core, if it is not optically isotropic, for example, there is a difference in the transmission speed between the horizontal wave signal and the vertical wave signal, which causes noise and interference problems. Other optical isotropic applications include prism sheet substrates, optical disk substrates, flat panel display substrates, and the like.
Next, the manufacturing method of the acrylic resin containing a glutaric anhydride unit is explained in full detail.

  Unsaturated carboxylic acid monomer (i) and unsaturated carboxylic acid alkyl ester monomer (ii) which give the glutaric anhydride unit represented by the general formula (1) by the subsequent heating step, and other vinyls In the case where a monomer unit is included, the vinyl monomer (iii) providing the unit is polymerized to form a copolymer (a), and then the copolymer (a) is present in the presence of a suitable catalyst. It can be produced by heating in the absence or in the absence of an intramolecular cyclization reaction by dealcoholization and / or dehydration. In this case, the carboxyl group of the unsaturated carboxylic acid unit of 2 units is typically dehydrated by heating the copolymer (a), or the adjacent unsaturated carboxylic acid unit and unsaturated carboxylic acid alkyl ester unit. 1 unit of the glutaric anhydride unit is generated by the elimination of the alcohol.

  The unsaturated carboxylic acid monomer (i) used in this case is not particularly limited, and can be copolymerized with another vinyl compound (iii). The body can be used.

(However, R ³ represents hydrogen or an alkyl group having 1 to 5 carbon atoms.)
In particular, acrylic acid and methacrylic acid are preferable from the viewpoint of excellent thermal stability, and methacrylic acid is more preferable. These can be used alone or in combination of two or more thereof. The unsaturated carboxylic acid monomer (i) represented by the general formula (i) gives a carboxylic acid unit having a structure represented by the following general formula (i-2) when copolymerized.

(However, R ³ represents hydrogen or an alkyl group having 1 to 5 carbon atoms.)
As the unsaturated carboxylic acid alkyl ester monomer (ii), methyl methacrylate is preferable from the viewpoint of the transparency and weather resistance of the resulting film. Further, one or more kinds of other unsaturated carboxylic acid alkyl ester monomers can be used together with methyl methacrylate. Although there is no restriction | limiting in particular as another unsaturated carboxylic acid alkylester monomer, As a preferable example, what is represented by the following general formula (ii) can be mentioned.

(Wherein, R ⁴ represents hydrogen or an aliphatic having 1 to 5 carbon atoms, or alicyclic hydrocarbon group, R ⁵ represents any substituent other than hydrogen.)
Among these, R ⁵ is particularly preferably an acrylate ester and / or a methacrylic ester having an aliphatic or alicyclic hydrocarbon group having 1 to 6 carbon atoms or a hydrocarbon group having a substituent. The unsaturated carboxylic acid alkyl ester monomer represented by the general formula (ii) gives a carboxylic acid alkyl ester unit having a structure represented by the following general formula (ii-2) when copolymerized.

(Wherein, R ⁴ represents hydrogen or an aliphatic having 1 to 5 carbon atoms, or alicyclic hydrocarbon group, R ⁵ represents any substituent other than hydrogen.)
Preferable specific examples of the unsaturated carboxylic acid alkyl ester monomer (ii) other than methyl methacrylate include ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, ( T-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate , (Meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid 2,3,4,5,6-pentahydroxyhexyl, (meth) acrylic acid 2,3,4,5-tetrahydroxypentyl and the like. .

  Moreover, in manufacture of the acrylic resin (A) used by this invention, you may use another vinyl-type monomer (iii) in the range which does not impair the effect of this invention. Preferable specific examples of the other vinyl monomers (iii) include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene and pt-butylstyrene. Aromatic vinyl monomers such as, vinyl cyanide monomers such as acrylonitrile, methacrylonitrile, ethacrylonitrile, allyl glycidyl ether, styrene-p-glycidyl ether, p-glycidyl styrene, maleic anhydride, anhydrous Itaconic acid, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide, aminoethyl acrylate, Propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, cyclohexylaminoethyl methacrylate, N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine , P-aminostyrene, 2-isopropenyl-oxazoline, 2-vinyl-oxazoline, 2-acryloyl-oxazoline, 2-styryl-oxazoline, etc., but transparency, birefringence, chemical resistance And a monomer that does not contain an aromatic ring is more preferably used. These may be used alone or in combination of two or more.

  As for the polymerization method of the acrylic resin (A), a known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc., basically by radical polymerization can be used, but in terms of fewer impurities. Solution polymerization, bulk polymerization, and suspension polymerization are particularly preferred.

  The polymerization temperature is not particularly limited, but from the viewpoint of color tone, a monomer mixture containing an unsaturated carboxylic acid monomer and an unsaturated carboxylic acid alkyl ester monomer is polymerized at a polymerization temperature of 95 ° C. or less. Is preferred. Furthermore, in order to further suppress the coloration after the heat treatment, a preferable polymerization temperature is 85 ° C. or less, and particularly preferably 75 ° C. or less. The lower limit of the polymerization temperature is not particularly limited as long as the polymerization proceeds, but is usually 50 ° C. or higher, preferably 60 ° C. or higher from the viewpoint of productivity considering the polymerization rate. For the purpose of improving the polymerization yield or the polymerization rate, it is possible to raise the polymerization temperature according to the progress of the polymerization. In this case, the upper limit temperature is preferably controlled to 95 ° C. or less, and the polymerization start temperature Is preferably performed at a relatively low temperature of 75 ° C. or lower. The polymerization time is not particularly limited as long as it is a sufficient time to obtain the required degree of polymerization, but is preferably in the range of 60 to 360 minutes, particularly preferably in the range of 90 to 180 minutes from the viewpoint of production efficiency.

  The acrylic resin (A) used for the thermoplastic resin film of the present invention preferably has a weight average molecular weight of 80,000 to 150,000. In the acrylic resin (A) having such a molecular weight, the copolymer (a) is previously controlled to have a desired molecular weight, that is, a weight average molecular weight of 50,000 to 150,000 at the time of producing the copolymer (a). Can be achieved. When the weight average molecular weight exceeds 150,000, there is a tendency to color at the time of heat degassing in the subsequent step. On the other hand, when the weight average molecular weight is less than 50,000, the mechanical strength of the acrylic resin film tends to decrease.

  There is no restriction | limiting in particular about the molecular weight control method of a copolymer (a), For example, a conventionally well-known technique is applicable. For example, controlled by the amount of radical polymerization initiators such as azo compounds and peroxides, or the amount of chain transfer agents such as alkyl mercaptans, carbon tetrachloride, carbon tetrabromide, dimethylacetamide, dimethylformamide, triethylamine, etc. can do. In particular, a method of controlling the amount of alkyl mercaptan added as a chain transfer agent can be preferably used from the viewpoint of stability of polymerization, ease of handling, and the like.

  Examples of the alkyl mercaptan used in the present invention include n-octyl mercaptan, t-dodecyl mercaptan, n-dodecyl mercaptan, n-tetradecyl mercaptan, n-octadecyl mercaptan and the like. Among them, t-dodecyl mercaptan, n-dodecyl mercaptan is preferably used.

  The addition amount of these alkyl mercaptans is not particularly limited as long as it is controlled to the specific molecular weight of the present invention, but is usually 0.2 to 5. with respect to 100 parts by weight of the total amount of the monomer mixture. 0 parts by weight, preferably 0.3 to 4.0 parts by weight, more preferably 0.4 to 3.0 parts by weight.

  A method for producing a thermoplastic polymer containing a glutaric anhydride unit by heating the copolymer (a) in the present invention and carrying out an intramolecular cyclization reaction by (i) dehydration and / or (b) dealcoholization. Although there is no particular limitation, a method of manufacturing through a heated extruder having a vent, or a method of manufacturing in an inert gas atmosphere or an apparatus that can be heated and devolatilized under reduced pressure is preferable from the viewpoint of productivity. Among them, when an intramolecular cyclization reaction is carried out by heating in the presence of oxygen, the yellowness tends to deteriorate, so it is preferable to sufficiently substitute the inside of the system with an inert gas such as nitrogen. As a particularly preferable apparatus, for example, a single screw extruder equipped with a “unimelt” type screw, a twin screw, a three screw extruder, a continuous or batch kneader type kneader, etc. can be used. The machine can be preferably used. Moreover, it is more preferable that the apparatus has a structure capable of introducing an inert gas such as nitrogen into them. For example, as a method for introducing an inert gas such as nitrogen into a twin-screw extruder, a method of connecting a pipe of an inert gas stream of about 10 to 100 liters / minute from the upper part and / or the lower part of the hopper can be mentioned. .

  The temperature for the devolatilization by the above method is not particularly limited as long as it is a temperature at which an intramolecular cyclization reaction occurs due to (i) dehydration and / or (b) dealcoholization, but preferably in the range of 180 to 300 ° C. In particular, a range of 200 to 280 ° C. is preferable.

  In addition, the time for heating and devolatilization in this case is not particularly limited and can be appropriately set according to the desired copolymer composition, but is usually 1 minute to 60 minutes, preferably 2 minutes to 30 minutes, especially 3 to 3. A range of 20 minutes is preferred. In particular, the length / diameter ratio (L / D) of the extruder screw is preferably 40 or more in order to secure a heating time for allowing sufficient intramolecular cyclization reaction to proceed using an extruder. When an extruder with a short L / D is used, a large amount of unreacted unsaturated carboxylic acid units remain, so that the reaction proceeds again during the heat molding process, and there is a tendency for silver and bubbles to be seen in the molded product and molding retention. Sometimes the color tends to deteriorate significantly.

  Furthermore, in the present invention, when the copolymer (a) is heated by the above method or the like, one or more of acid, alkali and salt compounds may be added as a catalyst for promoting the cyclization reaction to glutaric anhydride. it can. The addition amount is not particularly limited, and is preferably about 0.01 to 1 part by weight per 100 parts by weight of the copolymer (a). There are no particular restrictions on the types of these acids, alkalis, and salt compounds, and examples of the acid catalyst include hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, phosphoric acid, phosphorous acid, phenylphosphonic acid, and methyl phosphate. It is done. Examples of the basic catalyst include metal hydroxides, amines, imines, alkali metal derivatives, alkoxides, ammonium hydroxide salts and the like. Furthermore, examples of the salt-based catalyst include metal acetates, metal stearates, metal carbonates, and the like. However, it is necessary to add in a range where the color possessed by the catalyst does not adversely affect the coloring of the thermoplastic polymer and the transparency is not lowered. Among them, the compound containing an alkali metal can be preferably used because it exhibits an excellent reaction promoting effect with a relatively small addition amount. Specifically, hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, alkoxide compounds such as sodium methoxide, sodium ethoxide, sodium phenoxide, potassium methoxide, potassium ethoxide, and potassium phenoxide, lithium acetate And organic carboxylates such as sodium acetate, potassium acetate and sodium stearate, among which sodium hydroxide, sodium methoxide, lithium acetate and sodium acetate can be preferably used.

  The content of the glutaric anhydride unit represented by the general formula (1) in the acrylic resin (A) used in the present invention is 5-45 mol%, more preferably 10-40 mol%, most preferably 15- 25 mol%. When a glutaric anhydride unit is less than 5 mol%, a glass transition point (Tg) may fall and the heat resistance improvement effect may become small. Further, if the glutaric anhydride unit exceeds 45 mol%, the toughness may be deteriorated. Improvement in heat resistance and improvement in toughness are in a trade-off relationship and can be adjusted by the content of glutaric anhydride units. For this reason, it is preferable to employ | adopt arbitrary values for content of a glutaric anhydride unit within the range of 5-45 mol% according to a use.

  Examples of other components contained in the acrylic resin (A) include a methyl methacrylate unit and a methacrylic acid unit. The methyl methacrylate unit is preferably contained, and the content of the methyl methacrylate unit is From the viewpoint of optical isotropy and toughness, 55 to 95 mol% is preferable. Furthermore, from the viewpoint of hydrolysis resistance and optical isotropy of the acrylic resin (A), it is preferable that the sum of the content of methyl metal acrylate units and the content of glutaric anhydride units is 90 mol% or more. When the sum of the content of the methyl metal acrylate unit and the content of the glutaric anhydride unit is less than 90 mol%, the optical isotropy may be impaired or the hydrolysis resistance may deteriorate.

  In addition to the glutaric anhydride unit and the methyl methacrylate unit, a methacrylic acid unit that is a precursor of the glutaric anhydride unit may be included. When a methacrylic acid unit or a methyl methacrylate unit is adjacent to a methacrylic acid unit, it is not preferable because dehydration or dealcoholization occurs during heating in a process such as film formation or stretching, which may cause foaming. Since dehydration or dealcoholization reaction cannot occur if glutaric anhydride units are adjacent, methacrylic acid units may be included.

A proton nuclear magnetic resonance ( ¹ H-NMR) measuring machine is used for quantification of each component unit in the acrylic resin (A) used in the present invention. ^{In the 1} H-NMR method, for example, in the case of a copolymer consisting of a glutaric anhydride unit, methacrylic acid, and methyl methacrylate, the spectral assignment in a dimethyl sulfoxide heavy solvent is 0.5 to 1.5 ppm peak. Is hydrogen of α-methyl group of methacrylic acid, methyl methacrylate and glutaric anhydride ring compound, peak of 1.6 to 2.1 ppm is hydrogen of methylene group of polymer main chain, peak of 3.5 ppm is methyl methacrylate The carboxylic acid ester (—COOCH ₃ ) of hydrogen, the peak at 12.4 ppm can determine the copolymer composition from the carboxylic acid hydrogen of methacrylic acid and the integral ratio of the spectrum. In addition to the above, in the case of a copolymer containing styrene as another copolymer component, hydrogen of an aromatic ring of styrene is seen at 6.5 to 7.5 ppm, and the copolymer is similarly obtained from the spectral ratio. The composition can be determined.

  Moreover, the acrylic resin (A) used for this invention can contain an unsaturated carboxylic acid unit and / or other vinyl-type monomer units which can be copolymerized in an acrylic resin (A).

  The amount of unsaturated carboxylic acid units contained in the acrylic resin (A) used in the present invention is preferably 10 mol% or less, that is, 0 to 10 mol%, more preferably 0 to 5 mol%, most preferably 0 to 0 mol%. 1 mol%. When the unsaturated carboxylic acid unit exceeds 10 mol%, the colorless transparency and the residence stability tend to be lowered.

  Further, the amount of other vinyl monomer units copolymerizable with the acrylic resin (A) is preferably 5 mol% or less, that is, in the range of 0 to 5 mol%, more preferably 0 to 3 mol%. In particular, when an aromatic vinyl monomer unit such as styrene is contained and the content exceeds the above range, colorless transparency, optical isotropy, and chemical resistance tend to decrease.

  The glass transition point (Tg) of the thermoplastic resin used in the present invention is 110 ° C. or higher, preferably 120 ° C. or higher, more preferably 125 ° C. or higher. When Tg is less than 110 ° C., the heat resistance is inferior. For example, when processing a hard coat or the like on a film, problems such as poor flatness or increased curling due to shrinkage occur. In addition, when used inside the display, the image may be deteriorated due to a dimensional change due to internal heat or deterioration of flatness. Further, the upper limit of the glass transition point (Tg) is not particularly specified, but it is usually 200 ° C. or less because of problems in resin production and melt extrudability during film production. The method for controlling the glass transition point (Tg) to the above range is not particularly limited, but can be appropriately adjusted by, for example, the composition and molecular weight of the resin. In particular, for acrylic resins, for example, as described above, the glass transition point (Tg) can be adjusted by the ratio of the cyclized structure introduced into the molecule.

  In the present invention, by dispersing the acrylic elastic particles (B) in the acrylic resin (A), excellent toughness and impact resistance are imparted without significantly detracting from the excellent characteristics of the acrylic resin (A). be able to. As content of an acrylic elastic body particle (B), 5-50 mass% is preferable, More preferably, it is 10-30 mass%. When the acrylic elastic particle (B) is less than 5% by mass, the toughness of the film may be inferior or the haze may not be controlled to a desired value. When the acrylic elastic particle (B) exceeds 50% by mass, the heat resistance may be insufficient, or the haze may not be controlled to a desired value.

  The acrylic elastic particles (B) are composed of a layer containing one or more rubbery polymers and one or more layers composed of different polymers, and these layers are adjacent to each other. Graft copolymer made by copolymerizing a monomer mixture composed of vinyl monomers in the presence of so-called core-shell type multilayer structure polymer (BM) and rubbery polymer. Combined (BG) etc. can be used preferably.

  As the core-shell type multilayer structure polymer (BM) used in the present invention, the number of layers constituting the core-shell type polymer (BM) is not particularly limited, and may be two or more layers, or three or more layers or Although it may be four or more layers, it is important that the polymer has a multilayer structure polymer having at least one rubber layer therein.

  In the multilayer structure polymer (BM) of the present invention, the type of the rubber layer is not particularly limited as long as it is composed of a polymer component having rubber elasticity. For example, a rubber composed of a polymer obtained by polymerizing an acrylic component, a silicone component, a styrene component, a nitrile component, a conjugated diene component, a urethane component or an ethylene component, a propylene component, an isobutene component, and the like can be given. Preferred rubbers include, for example, acrylic components such as ethyl acrylate units and butyl acrylate units, silicone components such as dimethylsiloxane units and phenylmethylsiloxane units, styrene components such as styrene units and α-methylstyrene units, acrylonitrile units, A rubber composed of a nitrile component such as a methacrylonitrile unit and a conjugated diene component such as a butanediene unit or an isoprene unit. A rubber composed of a combination of two or more of these components is also preferable. For example, (1) acrylic components such as ethyl acrylate units and butyl acrylate units and silicones such as dimethylsiloxane units and phenylmethylsiloxane units. Rubber composed of components, (2) rubber composed of acrylic components such as ethyl acrylate units and butyl acrylate units, and styrene components such as styrene units and α-methylstyrene units, (3) ethyl acrylate units and Rubber composed of acrylic components such as butyl acrylate units and conjugated diene components such as butanediene units and isoprene units, and (4) acrylic components such as ethyl acrylate units and butyl acrylate units, dimethylsiloxane units and phenylmethylsiloxanes Unit etc. Rubber composed of styrene component such as silicone component and styrene units and α- methyl styrene units and the like. In addition to these components, a rubber obtained by crosslinking a copolymer composed of a crosslinking component such as a divinylbenzene unit, an allyl acrylate unit, and a butylene glycol diacrylate unit is also preferable.

  In the multilayer structure polymer (BM) of the present invention, the type of layer other than the rubber layer is not particularly limited as long as it is composed of a polymer component having thermoplasticity, but from the rubber layer. Is preferably a polymer component having a high glass transition temperature. Polymers having thermoplastic properties include unsaturated carboxylic acid alkyl ester units, unsaturated carboxylic acid units, unsaturated glycidyl group-containing units, unsaturated dicarboxylic acid anhydride units, aliphatic vinyl units, and aromatic vinyls. Examples include polymers containing at least one unit selected from system units, vinyl cyanide units, maleimide units, unsaturated dicarboxylic acid units and other vinyl units. Among them, unsaturated carboxylic acids A polymer containing at least one unit selected from an alkyl ester unit, an unsaturated glycidyl group-containing unit, and an unsaturated dicarboxylic acid anhydride unit is preferable, and further, an unsaturated glycidyl group-containing unit and an unsaturated dicarboxylic acid A polymer containing at least one unit selected from anhydride-based units is more preferable.

  Although it does not specifically limit as a monomer used as the raw material of the said unsaturated carboxylic-acid alkylester type | system | group unit, (meth) acrylic-acid alkylester is used preferably. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, (meth) acrylic N-hexyl acid, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, stearyl (meth) acrylate, octadecyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, ( Chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6 (meth) acrylic acid -Pentahydroxyhexyl, 2,3,4,5-tetrahydroxypentyl (meth) acrylate, amino acid acrylate Examples include ethyl, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, cyclohexylaminoethyl methacrylate, and the like, which are highly effective in improving toughness and impact resistance. Methyl (meth) acrylate is preferably used. These units can be used alone or in combination of two or more.

  The unsaturated carboxylic acid monomer is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, maleic acid, and further a hydrolyzate of maleic anhydride. Acrylic acid is particularly excellent in terms of thermal stability. Methacrylic acid is preferable, and methacrylic acid is more preferable. These can be used alone or in combination.

  The monomer used as the raw material for the unsaturated glycidyl group-containing unit is not particularly limited, and is glycidyl (meth) acrylate, glycidyl itaconate, diglycidyl itaconate, allyl glycidyl ether, styrene-4-glycidyl ether. And 4-glycidylstyrene, and glycidyl (meth) acrylate is preferably used from the viewpoint that the effect of improving impact resistance is great. These units can be used alone or in combination of two or more.

  Examples of the monomer used as a raw material for the unsaturated dicarboxylic acid anhydride unit include maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, and aconitic anhydride, and the effect of improving impact resistance. From the standpoint of large, maleic anhydride is preferably used. These units can be used alone or in combination of two or more.

  Examples of the monomer that is a raw material for the aliphatic vinyl-based unit include ethylene, propylene, and butadiene. Examples of the monomer that is a raw material for the aromatic vinyl-based unit are styrene, α-methylstyrene, 1 -Vinyl naphthalene, 4-methyl styrene, 4-propyl styrene, 4-cyclohexyl styrene, 4-dodecyl styrene, 2-ethyl-4-benzyl styrene, 4- (phenylbutyl) styrene, halogenated styrene, etc. Acrylonitrile, methacrylonitrile, ethacrylonitrile, etc. are used as the raw material for the vinyl-based unit, and maleimide, N-methylmaleimide, N-ethylmaleimide are used as the monomer for the maleimide-based unit. N-propylmaleimide, N-isopropylmaleimide, Examples of monomers that can be used as raw materials for the unsaturated dicarboxylic acid units include maleic acid and maleic acid such as -cyclohexylmaleimide, N-phenylmaleimide, N- (p-bromophenyl) maleimide, and N- (chlorophenyl) maleimide. Monoethyl ester, itaconic acid, phthalic acid, and the like, which are monomers used as raw materials for the other vinyl units, include acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide, N- Vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine, p-aminostyrene, 2-isopropenyl-oxazoline, 2-vinyl-oxazoline, 2-acryloyl-oxazoline, and 2-styrene Examples include ril-oxazoline, and these monomers can be used alone or in combination of two or more.

  In the multilayer structure polymer (BM) containing the rubbery polymer of the present invention, the kind of the outermost layer is not particularly limited, and is an unsaturated carboxylic acid alkyl ester unit or an unsaturated carboxylic acid unit. Unsaturated glycidyl group-containing units, aliphatic vinyl units, aromatic vinyl units, vinyl cyanide units, maleimide units, unsaturated dicarboxylic acid units, unsaturated dicarboxylic anhydride units, and other vinyl types And at least one selected from polymers containing units and the like. Among them, unsaturated carboxylic acid alkyl ester units, unsaturated carboxylic acid units, unsaturated glycidyl group-containing units, and unsaturated dicarboxylic anhydrides At least one selected from polymers containing system units is preferred, and further unsaturated carboxylic acid alkyl ester system units, unsaturated Polymers containing carboxylic acid units is more preferable.

  Furthermore, in the present invention, when the outermost layer in the multilayer polymer (BM) is a polymer containing an unsaturated carboxylic acid alkyl ester unit and an unsaturated carboxylic acid unit, by heating, In the same manner as in the production of the thermoplastic copolymer (A) of the present invention described above, the intramolecular cyclization reaction proceeds, and the glutaric anhydride unit represented by the general formula (1) is generated. It was. Therefore, a multilayer structure polymer (BM) having a polymer containing an unsaturated carboxylic acid alkyl ester unit and an unsaturated carboxylic acid unit unit in the outermost layer is blended with the thermoplastic copolymer (A). In the thermoplastic copolymer (A) which becomes a continuous phase (matrix phase) by heating and kneading under such conditions, the glutaric acid represented by the above general formula (1) is substantially formed in the outermost layer. By dispersing the multilayer structure polymer (BM) having a polymer containing an anhydride unit, a good dispersion state is possible without agglomeration, and improvement in mechanical properties such as impact resistance, It is considered that extremely high transparency can be expressed.

  The monomer used as the raw material for the unsaturated carboxylic acid alkyl ester unit herein is not particularly limited, but (meth) acrylic acid alkyl ester is preferred, and methyl (meth) acrylate is more preferred. Preferably used.

  Further, the monomer used as a raw material for the unsaturated carboxylic acid unit is not particularly limited, but (meth) acrylic acid is preferable, and methacrylic acid is more preferably used.

  As the constitution of the multilayer structure polymer (BM) of the present invention, the core layer (inner layer) is a rubber elastic body containing an alkyl acrylate unit and / or an aromatic vinyl unit, and the shell layer (outer layer) is From the viewpoint of toughness and impact resistance, a polymer containing an acrylic resin containing a glutaric anhydride unit is preferred. Specifically, the core layer (inner layer) is a butyl acrylate / styrene polymer, and the outermost layer. Is a copolymer of methyl methacrylate / glutaric anhydride unit represented by the above general formula (1), or methyl methacrylate / glutaric anhydride unit represented by the above general formula (1) / methacrylic acid heavy Those in which the core layer (inner layer) is a dimethylsiloxane / butyl acrylate polymer and the outermost layer is a methyl methacrylate polymer, and the core layer (inner layer) is butanediene Examples include styrene polymers whose outermost layer is a methyl methacrylate polymer, and those whose core layer (inner layer) is a butyl acrylate polymer and whose outermost layer is a methyl methacrylate polymer (“/”). Indicates copolymerization). Further, a preferable example is one in which either one or both of the rubber layer (inner layer) and the outermost layer is a polymer containing glycidyl methacrylate units. Among them, the core layer is butyl acrylate / styrene polymer, and the outermost layer is methyl methacrylate / a copolymer of glutaric anhydride units represented by the above general formula (1), or methyl methacrylate / the above general formula. In the resin composition, the glutaric anhydride unit represented by (1) / methacrylic acid polymer approximates the refractive index with the acrylic resin (A) that is the continuous phase (matrix phase), and Can be obtained, and as a result, the internal haze of the film can be reduced.

  As a weight average particle diameter of the multilayer structure polymer (BM) of this invention, it is preferable to set it as 50-300 nm, More preferably, it is 100-200 nm. When the weight average particle size is less than 50 nm, the toughness may not be sufficiently improved, and when it exceeds 300 nm, the internal haze may be deteriorated.

  In the multilayer structure polymer (BM) of the present invention, the weight ratio of the core and the shell is not particularly limited, but the core layer is 50 parts by weight or more with respect to 100 parts by weight of the entire multilayer structure polymer. 90 parts by weight or less, and more preferably 60 parts by weight or more and 80 parts by weight or less.

  As the multilayer structure polymer of the present invention, a commercially available product that satisfies the above-described conditions may be used, or it may be prepared by a known method.

  Commercially available products of multilayer structure polymers include, for example, “Metablene” manufactured by Mitsubishi Rayon Co., Ltd., “Kane Ace” manufactured by Kaneka Chemical Industry Co., Ltd., “Paraloid” manufactured by Kureha Chemical Industry Co., Ltd. “Staffyroid” manufactured by Kogyo Co., Ltd., “Parapet SA” manufactured by Kuraray Co., Ltd., and the like can be used.

  Specific examples of the rubber-containing graft copolymer (BG) that can be used as the acrylic elastic particles (B) of the present invention include unsaturated carboxylic acid esters in the presence of a rubbery polymer. A monomer mixture comprising a monomer, an unsaturated carboxylic acid monomer, an aromatic vinyl monomer, and, if necessary, other vinyl monomers copolymerizable therewith. And graft copolymers.

  The rubbery polymer used for the graft copolymer (B-G) is not particularly limited, but diene rubber, acrylic rubber, ethylene rubber, and the like can be used. Specific examples include polybutadiene, styrene-butadiene copolymer, block copolymer of styrene-butadiene, acrylonitrile-butadiene copolymer, butyl acrylate-butadiene copolymer, polyisoprene, butadiene-methyl methacrylate copolymer. , Butyl acrylate-methyl methacrylate copolymer, butadiene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-isoprene copolymer, and ethylene-acrylic acid Examples thereof include a methyl copolymer. These rubbery polymers can be used alone or in a mixture of two or more.

  As a weight average particle diameter of the rubber-like polymer which comprises the graft copolymer (BG) in this invention, it is preferable to set it as 50-300 nm, More preferably, it is 100-200 nm. When the average particle size is less than 50 nm, the toughness may not be sufficiently improved, and when it exceeds 300 nm, the internal haze may be deteriorated.

  The weight average particle diameter of the rubber polymer is the sodium alginate method described in “Rubber Age, Vol. 88, p. 484-490 (1960), by E. Schmidt, P. H. Biddison”, that is, sodium alginate. By using the fact that the diameter of the polybutadiene particles to be creamed differs depending on the concentration of the cream, it can be measured by a method of determining the particle size of 50% cumulative weight fraction from the weight proportion of cream and the cumulative weight fraction of sodium alginate concentration. .

  The graft copolymer (BG) in the present invention is 10 to 80 parts by weight, preferably 20 to 70 parts by weight, more preferably 100 parts by weight of the rubbery polymer with respect to 100 parts by weight of the graft copolymer (BG). In the presence of 30 to 60 parts by weight, it is obtained by copolymerizing 20 to 90 parts by weight, preferably 30 to 80 parts by weight, more preferably 40 to 70 parts by weight of the above monomer (mixture). When the ratio of the rubbery polymer is less than the above range or exceeds the above range, the impact strength and the surface appearance may be lowered.

  The graft copolymer (BG) may contain a non-grafted copolymer that is produced when a monomer mixture is graft copolymerized with a rubbery polymer. However, from the viewpoint of impact strength, the graft ratio is preferably 10 to 100%. Here, the graft ratio is a weight ratio of the grafted monomer mixture to the rubbery polymer. In addition, the intrinsic viscosity measured at 30 ° C. of the methylethylketone solvent of the ungrafted copolymer is not particularly limited, but 0.1 to 0.6 dl / g is a balance between impact strength and moldability. From the viewpoint of, it is preferably used.

  In the present invention, the intrinsic viscosity of the vinyl copolymer (BG) measured at 30 ° C. of the vinyl copolymer (BG) is not particularly limited, but it is 0.2 to 1.0 dl / g, which has impact strength and molding. It is preferably used from the viewpoint of balance with workability, and more preferably 0.3 to 0.7 dl / g.

  There is no restriction | limiting in particular in the manufacturing method of the graft copolymer (BG) in this invention, It can obtain by well-known polymerization methods, such as block polymerization, solution polymerization, suspension polymerization, and emulsion polymerization.

  Moreover, since the transparency can be obtained in the acrylic resin film of the present invention, it is preferable that the refractive indexes of the acrylic resin (A) and the acrylic elastic body particles (B) are approximate. Specifically, the difference in refractive index is preferably 0.010 or less, more preferably 0.005 or less, and particularly preferably 0.003 or less. In order to satisfy such a refractive index condition, a method of adjusting each monomer unit composition ratio of the acrylic resin (A) and / or a rubbery polymer or single polymer used for the acrylic elastic particles (B). The refractive index difference can be reduced by a method of adjusting the composition ratio of the monomer, and an acrylic resin film excellent in transparency can be obtained. Specifically, the core layer (inner layer) is butyl acrylate / styrene polymer, and the outermost layer is methyl methacrylate / a copolymer of glutaric anhydride units represented by the above general formula (1), or methacrylic acid Methyl / glutaric anhydride unit represented by the above general formula (1) / methacrylic acid polymer. Here, as a method of blending acrylic elastic particles and other additives with acrylic resin, for example, after blending acrylic resin or acrylic resin and other additive components in advance, usually at 200 to 350 ° C., uniaxial or biaxial A method of uniformly melt-kneading with a shaft extruder can be used.

  In the melt-kneading, a cyclization reaction of unsaturated carboxylic acid monomer units such as shell portions imparted to the acrylic elastic particles and unsaturated carboxylic acid alkyl ester monomer units can be performed simultaneously.

  Here, the difference in refractive index means that the acrylic resin film of the present invention is sufficiently dissolved in a solvent in which the acrylic resin (A) is soluble to obtain a cloudy solution, which is subjected to an operation such as centrifugation. The solvent is separated into a soluble part and an insoluble part, and the soluble part (acrylic resin (A)) and the insoluble part (acrylic elastic particle (B)) are purified, respectively, and then the measured refractive index (23 ° C., measured) Wavelength: 550 nm).

  In addition, the copolymer composition of the acrylic resin (A) and the acrylic elastic particles (B) in the substantial acrylic resin film is obtained by separating each of the components individually by separating the soluble component and the insoluble component using the solvent. It can be analyzed.

  The thermoplastic resin film in the present invention has an in-plane retardation (Δnd) of 10 nm or less, preferably 5 nm or less, more preferably 2 nm or less. Moreover, the thickness direction retardation (Rth) of the thermoplastic resin film in this invention is -10-10 nm, Preferably it is -8-8 nm, More preferably, it is -5-5 nm. If the absolute value of the in-plane retardation (Δnd) or thickness direction retardation (Rth) exceeds 10 nm, the optical isotropy deteriorates, so it is used for liquid crystal display applications such as polarizer protective films and optical disk protective films. If this occurs, problems such as unevenness of the screen and a decrease in the frequency of data errors may occur. In applications where optical isotropy is required, the absolute values of the in-plane retardation (Δnd) and the thickness direction retardation (Rth) are preferably small, but in reality, the lower limit is considered to be about 0.1 nm. In order to obtain such an optically isotropic thermoplastic resin film, as described above, the resin contains an alicyclic structure such as a glutaric anhydride structure, a lactone ring structure, a norbornene structure, or a cyclopentane structure. It is most preferable, and it is effective not to introduce an additive or a copolymerization component that develops a phase difference, or to reduce the draw ratio during film formation.

The thermoplastic resin film of the present invention, in particular the acrylic resin film is preferably photoelastic coefficient of ^{-5 × 10 -12 m 2 / N~5} × 10 -12 m 2 / N. By photoelastic coefficient of ^{-5 × 10 -12 m 2 / N~5} × 10 -12 m 2 / N, when used in a liquid crystal television having a large screen, the other members are bonded together with an acrylic resin film When the acrylic resin film is stressed due to thermal expansion or residual stress, the change in phase difference is small, which is preferable. More photoelastic coefficient is small, preferably for the phase difference change is small with respect to stress, and more preferably from ^{-3 × 10 -12 m 2 / N~3} × 10 -12 m 2 / N. Although the photoelastic coefficient of an acrylic resin film is generally small, if styrene or maleimide is copolymerized or an aromatic substituent is introduced to improve heat resistance, the photoelastic coefficient is also increased. The acrylic resin film described above can achieve both improved heat resistance and a low photoelastic coefficient due to the glutaric anhydride structure.

  In the thermoplastic resin film of the present invention, the inside of the film does not scatter light, and has excellent handleability and workability by taking a configuration having slight wavy irregularities on the film surface, and It becomes possible to express high transparency. Specifically, the film has a structure that does not scatter light, and has a structure with slight undulations on the surface, so that the film is slippery and air bleed when wound into a roll. By filling the surface asperity shape by performing processing such as providing a functional layer such as a hard coat layer, an adhesive layer, or an antireflection layer on the surface of the thermoplastic resin film, which can improve the charging property, etc. Light scattering is reduced, and high transparency can be achieved. That is, such a function can be expressed by controlling the total haze within a certain range while keeping the internal haze of the film low.

  That is, in the thermoplastic resin film of the present invention, the internal haze is 1.0% or less, preferably 0.5% or less, more preferably 0.3% or less. If the internal haze exceeds 1.0%, light scattering increases and the image may be blurred or the accuracy may be poor. Moreover, in the thermoplastic resin film of the present invention, the total haze is 1.6% or more, preferably 1.6 to 5.0%, more preferably 1.6 to 3.0%. When the total haze is less than 1.6%, handling properties such as winding property and running property may be inferior. The upper limit of the total haze is not particularly limited, but is preferably less than 5.0% from the viewpoint of reducing the haze value after surface processing.

  Moreover, about the thermoplastic resin film in this invention, 1.0% or more of the surface haze calculated by total haze-internal haze is preferable. When the surface haze is less than 1.0%, the degree of improvement in handleability may be insufficient. Further, the upper limit value of the surface haze is not particularly limited, but is preferably less than 5.0% from the same viewpoint as the total haze. In addition, surface haze is use of the ratio of the light scattered by the unevenness | corrugation of a film surface, and becomes an parameter | index showing the waviness-like unevenness | corrugation property of a surface.

  In order to produce a thermoplastic resin film having such an internal haze and an external haze, for example, a method of forming a laminated structure having a layer containing no particles inside, a layer containing particles on the surface, and a film production process And a method of making minute irregularities on the surface. In particular, as a preferable method for expressing high transparency after processing, as described above, the thermoplastic resin contains elastic particles having a refractive index difference of 0.010 or less from the thermoplastic resin, and a film. In the production process, there is a method in which fine irregularities due to the elastic particles are expressed on the film surface. By containing elastic particles with a small refractive index difference from the thermoplastic resin, light scattering at the interface between the thermoplastic resin and elastic particles can be reduced, preventing scattering inside the film and achieving low internal haze. It becomes possible to do. Further, minute irregularities on the surface can be expressed by stretching a thermoplastic resin containing elastic particles having a small refractive index difference as described above when the film is processed into a film.

  However, for example, when a method in which a resin melt-extruded by an extruder is discharged from a die, cooled and formed on a cooling roll and then heated and stretched is used, the phase difference of the thermoplastic resin film is There is a problem that the optical isotropy tends to be lost due to the increase in size. Therefore, by stretching the molten resin discharged from the die until it is cooled on the roll, it is possible to develop surface irregularities without deteriorating the phase difference. When the draft ratio represented by the following formula is used as an index of the draw ratio until the molten resin discharged from the die is cooled on the drum, the draft ratio is preferably 10 or more, Preferably it is 15-50, More preferably, it is 15-25. When the draft ratio is less than 10, it may be difficult to form sufficient surface irregularities. Moreover, although the upper limit of draft ratio is not specifically limited, when it exceeds 100, it exists in the tendency which worsens the thickness nonuniformity of a film.

Draft ratio = (base width × average value in width direction of lip gap of base) / (film width on cooling roll × average thickness in width direction of film formed on cooling roll)
The temperature of the molten resin discharged from the die is preferably in the range of glass transition point (Tg) +100 to 150 ° C. of the main component, more preferably in the range of glass transition point (Tg) +120 to 140 ° C. . When the temperature of the molten resin exceeds the glass transition point (Tg) + 150 ° C., defects due to decomposition of the resin tend to increase. Further, when the temperature is lower than the glass transition point + 100 ° C., it is difficult to form unevenness on the surface, or the viscosity of the resin becomes too high and the flatness of the film tends to deteriorate.

  In the present invention, the average residence time from the molten resin extruder outlet to the T die outlet is preferably 30 minutes to 60 minutes. If the average residence time affects the wavy uneven shape formed on the surface, and if it is less than 30 minutes, sufficient unevenness may not be formed and the handleability may deteriorate. Moreover, when it exceeds 60 minutes, foreign materials, such as a decomposition product of a molten resin and a gelled material, increase, and the quality of a film may deteriorate. The average residence time here was defined as the time obtained by dividing the molten resin filling weight calculated from the internal volume between the extruder outlet and the die outlet by the discharge amount.

  The thermoplastic resin film in the present invention preferably has a single layer structure by a melt extrusion method. In the case of using a solution casting method in which a resin is dissolved in a solvent to form a sheet, there is a concern that the cost increases or environmental pollution due to the solvent occurs. Moreover, when it is set as a composite layer structure, the intensity | strength between layers becomes inadequate and problems, such as peeling, may arise.

  The thickness of the thermoplastic resin film of the present invention is not particularly limited, but is preferably 1 to 500 μm, more preferably 10 to 250 μm, still more preferably 20 to 150 μm, and particularly preferably 30 to 80 μm. If the film thickness is too thin, the strength may be insufficient or the productivity may be inferior. On the other hand, if the film thickness is too thick, the production cost may increase, the phase difference may deteriorate, Problems such as inferiority may occur.

  In the thermoplastic resin film of the present invention, it is preferable to add an ultraviolet absorber depending on the application. Any ultraviolet absorber can be used, and examples thereof include benzotriazole, salicylic acid ester, benzophenone, oxybenzophenone, cyanoacrylate, polymer, and inorganic. Further, since the ultraviolet absorber is kneaded and extruded together with the molten resin, it is preferably high in heat resistance, and preferably has a 10% heat loss temperature of 300 ° C. or higher.

  Examples of commercially available ultraviolet absorbers include “Adeka Stub”, “TINUVIN” (registered trademark) of Asahi Denka Kogyo Co., Ltd., “Uvinul” of BASF Corp., and UV absorber of Johoku Chemical Industry Co., Ltd.

  Aromatic polymer absorbs ultraviolet rays due to aromatics in the main chain, so there is a problem that the main chain is cut by ultraviolet rays and deteriorates, but the acrylic resin film of the present invention deteriorates because the main chain part does not absorb ultraviolet rays. This is preferable because a desired ultraviolet ray-cutting function can be imparted depending on the kind and amount of the ultraviolet absorber to be added. Furthermore, even if the ultraviolet absorber to add is an aromatic compound, since it exists at random, since a phase difference is hard to express, it is preferable.

  In the thermoplastic resin film of the present invention, the light transmittance at 380 nm is preferably 10% or less, more preferably 5% or less. For example, when used as a polarizer protective film, if the light transmittance at 380 nm exceeds 10%, the deterioration rate of the polarizer due to ultraviolet rays may increase.

  The addition amount of the ultraviolet absorber in the thermoplastic resin film of the present invention is preferably 0.1% by mass or more and 5% by mass or less. If it is less than 0.1% by mass, it is difficult to make the light transmittance at 380 nm 10% or less, and if it exceeds 5% by mass, problems such as coloration of the film may occur.

  The thermoplastic resin film of the present invention is not limited to the purpose of the present invention, and other acrylic resins (for example, polyethylene, polypropylene, acrylic resin, polyamide, polyphenylene sulfide resin, polyether ether ketone resin, polyester, polysulfone, Polyphenylene oxide, polyacetal, polyimide, polyetherimide, etc.), thermosetting resins (for example, phenol resin, melamine resin, polyester resin, silicone resin, epoxy resin, etc.) can be further added, and hindered Phenol, benzoate, and cyanoacrylate antioxidants, higher fatty acids, acid esters, and acid amides, and higher alcohol and other lubricants and plasticizers, montanic acid and its salts, Release agents such as tellurium, its half esters, stearyl alcohol, stearamide and ethylene wax, anti-coloring agents such as phosphites and hypophosphites, halogen flame retardants, phosphorus and silicone non-halogen flame retardants Additives such as flame retardants, nucleating agents, amine-based, sulfonic acid-based, polyether-based antistatic agents, pigments and other colorants may optionally be included. However, in light of the characteristics required by the application to be applied, it is necessary to add the additive within a range in which the color of the additive does not adversely affect the thermoplastic polymer and the transparency is not lowered.

  In the present invention, the method of blending the acrylic resin (A) with optional components such as acrylic elastic particles (B) or other additives is not particularly limited, and the acrylic resin (A) and other optional components are blended in advance. Thereafter, a method of uniformly melt-kneading with a single-screw or twin-screw extruder at 200 to 350 ° C. is preferably used. Moreover, when mix | blending acrylic elastic body particle | grains (B), the method of removing a solvent can be used after mixing in the solution of the solvent which melt | dissolves both (A) and (B) components.

  In addition, as a method for producing an acrylic resin used for the thermoplastic resin film of the present invention, a copolymer is obtained by copolymerizing a monomer mixture containing an unsaturated carboxylic acid monomer and an unsaturated carboxylic acid alkyl ester monomer. After obtaining (a) and then pre-blending the copolymer (a) and the acrylic elastic particles (B), usually at 200 to 350 ° C., by uniformly melt-kneading with a single-screw or twin-screw extruder, Simultaneously with the cyclization reaction of the component (a), the component (B) can be blended. At this time, a cyclization reaction can be simultaneously performed in the case where a part of the component (B) includes a copolymer composed of an unsaturated carboxylic acid monomer unit and an unsaturated carboxylic acid alkyl ester monomer unit. .

  The acrylic resin used in the acrylic resin film of the present invention is preferably filtered for the purpose of removing foreign substances. It can be usefully used as an optical application film by removing foreign substances. For the filtration, a known method can be used. A resin dissolved in a solvent such as tetrahydrofuran, acetone, methyl ethyl ketone, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone is appropriately filtered at a temperature of 25 ° C. or more and 100 ° C. or less. In order to prevent coloring of the resin, it is preferable to filter with sintered metal, porous ceramic, sand, wire mesh, or the like.

  A well-known method can be used for the manufacturing method of the thermoplastic resin film of this invention. That is, production methods such as an inflation method, a T-die method, a calendar method, a cutting method, a solution casting method (casting method), an emulsion method, and a hot press method can be used, but the T-die method is preferable.

In the case of a production method using an inflation method or a T-die method, an extruder type melt extrusion apparatus equipped with a single screw or twin screw can be used. Preferably, a twin screw kneading extruder with L / D = 25 or more and 120 or less is preferable in order to prevent coloring. The melt extrusion temperature for producing the film of the present invention is preferably 150 to 350 ° C, more preferably 200 to 300 ° C. Melt shear rate is preferably 1,000 S ^-1 or 5,000 S ^-1 or less. Moreover, when melt-kneading using a melt-extrusion apparatus, it is preferable to perform the melt-kneading under reduced pressure or the melt-kneading under nitrogen stream from a viewpoint of coloring suppression. Casting method is to measure the melted resin with a gear pump and then discharge it from a T-die die. On the cooled drum, electrostatic application method, air chamber method, air knife method, press roll method, which are known adhesion means per se. It is preferable to obtain an unstretched film by tightly cooling and solidifying it with a cooling medium such as a drum by rapid cooling to room temperature.

  For the purpose of improving the toughness of the thermoplastic resin film of the present invention, the unstretched film thus obtained may be stretched. The stretching may be uniaxial or biaxial, and known methods such as a sequential two-time stretching method and a simultaneous biaxial stretching method can be used.

  The thermoplastic resin film of the present invention is preferably hardened on at least one surface. The hard coat forming method is not particularly limited, and a known method can be used, and a method using a polyfunctional acrylate can be exemplified. Polyfunctional acrylates include 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, tetreethylene glycol diacrylate, tripropylene glycol diacrylate, neopentyl glycol diacrylate 1,4-butanediol dimethacrylate, poly (butanediol) diacrylate, tetraethylene glycol dimethacrylate, 1,3-butylene glycol diacrylate, triethylene glycol diacrylate, triisopropylene glycol diacrylate, polyethylene glycol diacrylate And diacrylates such as bisphenol A dimethacrylate; trimethylolpropane triacryl , Triacrylates such as trimethylolpropane trimethacrylate, pentaerythritol monohydroxytriacrylate and trimethylolpropane triethoxytriacrylate; tetraacrylates such as pentaerythritol tetraacrylate and di-trimethylolpropane tetraacrylate; and penta Mention may be made of pentaacrylates such as erythritol (monohydroxy) pentaacrylate.

  In addition to the hard coat layer, the thermoplastic resin film of the present invention can be provided with functional layers such as an antistatic layer, an ultraviolet absorbing layer, an adhesive layer, and an antireflection layer. These functional layers may be provided on both sides, or different functional layers may be provided on each side, or may be provided in a state of being laminated on the surface on one side.

  The film thus obtained is suitable for optical applications due to its excellent heat resistance and optical isotropy. Here, the optical application is a member for a display device, and particularly indicates a member used for a flat panel display such as a liquid crystal display, a plasma display, a field emission display, and an electroluminescence display. For example, plastic substrate, lens, polarizing plate, polarizing plate protective film, ultraviolet absorbing film, infrared absorbing film, electromagnetic wave shielding film, prism sheet, prism sheet substrate, Fresnel lens, optical disk substrate, optical disk substrate protective film, light guide plate, Retardation film, light diffusion film, viewing angle widening film, reflection film, antireflection film, antiglare film, brightness enhancement film, prism sheet, conductive film for touch panel can be exemplified, and polarizing film protective film especially from its optical isotropy As useful.

[Measurement method of physical properties]
Hereinafter, the configuration and effects of the present invention will be described more specifically with reference to examples. Of course, the present invention is not limited to the following examples. Prior to the description of each example, various physical property measurement methods employed in the example will be described. “Part by weight” is used in the same meaning as “part by mass”.

(1) Glass transition temperature Glass transition temperature (Tg)
After storing the film in a desiccator for 24 hours, about 10 mg of the sample is sealed in a hermetic pan and the temperature is increased at 20 ° C./min in a nitrogen atmosphere using a differential scanning calorimeter (TA Instrument Q100 type). Measured at temperature rate. The measurement was an average value of two times. As the glass transition temperature (Tg), the midpoint glass transition temperature (Tmg) of JIS K7121 (1987) is adopted.

(2) Haze (A) Total haze The total haze of the film at 23 ° C. was measured based on JIS K7105 (1981) 6.4 haze (cloudiness value). The measurement was performed 3 times and the average value was defined as the total haze.

(B) Internal haze The haze value in tetralin of the film was defined as internal haze. The quartz cell was filled with tetralin (for spectrum produced by Nacalai Tesque Co., Ltd.), the film was immersed in tetralin in the quartz cell, and the haze value was measured in the same manner as for all hazes to obtain internal haze.

(C) Surface haze Based on the value calculated | required by said (A) (B), the surface haze was computed by calculating "all the haze"-"internal haze".

(3) In-plane retardation (Δnd), thickness direction retardation (Rth)
Elliptical polarization measuring device (KOBRA-WPR) and phase difference measuring device KOBRA-RE (software for KOBRA-WR) Ver. 1.21 was used. The measurement is performed in a single N calculation mode of incident angle dependence measurement, using a low phase difference measurement method, with the slow axis as the tilt center axis and an incident angle of 40 ° (wavelength 590 nm). (Δnd) and thickness direction retardation (Rth) were obtained. The R0 value that is the phase difference at an incident angle of 0 ° was defined as the in-plane phase difference (Δnd). Moreover, the measurement was performed on a sample stored for 24 hours in a desiccator, and the average value of N = 5 times was defined as an in-plane retardation (Δnd) and a thickness direction retardation (Rth).

(4) Light transmittance at 380 nm Measurement was performed using the following apparatus, and transmittance corresponding to light at a wavelength of 380 nm was determined from the obtained transmittance data. The measurement was performed once.

Transmittance (%) = (T1 / T0) × 100
However, T1 is the intensity | strength of the light which passed the sample, and T0 is the intensity | strength of the light which passed the air of the same distance except not passing a sample.

Apparatus: UV measuring instrument U-3410 (manufactured by Hitachi Instruments)
Wavelength range: Measures a range of 300 nm to 400 nm Measurement speed: 120 nm / min Measurement mode: Transmission (5) Photoelastic coefficient (10 ⁻¹² m ² / N)
A sample having a short side of 1 cm and a long side of 7 cm was cut out. Using this sample, TRANSDUCER U3C1-5K manufactured by Shimadzu Corp., a check (1 cm / mm ² (9.81 × 10 ⁶ Pa)) was applied in the long side direction with 1 cm between the top and bottom. In this state, Re (nm) was measured using a polarizing microscope 5892 manufactured by Nikon Corporation. Sodium D line (589 nm) was used as a light source. These numerical values were applied to photoelastic coefficient = Re / (d × F) to calculate the photoelastic coefficient. The measurement was performed once.

(6) Refractive Index, Refractive Index Difference Acetone is added to the film and refluxed for 4 hours, and this solution is centrifuged at 9,000 rpm for 30 minutes to obtain acetone-soluble (component (A)) and insoluble ((B) Component). These were dried under reduced pressure at 60 ° C. for 5 hours. Each of the obtained solids was press-molded at 250 ° C. to form a film having a thickness of 0.1 mm, and then the refractive index at 23 ° C. and 550 nm wavelength was measured with an Abbe refractometer (manufactured by Atago Co., Ltd., DR-M2). It was measured. In addition, the absolute value was used about the refractive index difference of (A) component and (B) component. The measurement was performed once.

(7) Weight average molecular weight (absolute molecular weight)
The obtained thermoplastic polymer was gel permeation chromatograph (pump: 515 type, manufactured by Waters, Inc.) equipped with a DAWN-DSP type multi-angle light scattering photometer (manufactured by Wyatt Technology) using dimethylformamide as a solvent. The weight average molecular weight (absolute molecular weight) was measured using TSK-gel-GMHXL (manufactured by Tosoh Corporation).

(8) Composition of each component The film was dissolved in acetone, and this solution was centrifuged at 9,000 rpm for 30 minutes to separate into an acetone soluble component and an acetone insoluble component. The acetone-soluble component was dried under reduced pressure at 60 ° C. for 5 hours, and each component unit was quantified to identify each component composition of the acrylic resin.

Quantification of each component unit was performed by a proton nuclear magnetic resonance ( ¹ H-NMR) method. ^{In the 1} H-NMR method, for example, in the case of a copolymer consisting of a glutaric anhydride unit, methacrylic acid, and methyl methacrylate, the spectral assignment in a dimethyl sulfoxide heavy solvent is 0.5 to 1.5 ppm peak. Is hydrogen of α-methyl group of methacrylic acid, methyl methacrylate and glutaric anhydride ring compound, peak of 1.6 to 2.1 ppm is hydrogen of methylene group of polymer main chain, peak of 3.5 ppm is methyl methacrylate The carboxylic acid ester (—COOCH ₃ ) of hydrogen, the peak at 12.4 ppm can determine the copolymer composition from the carboxylic acid hydrogen of methacrylic acid and the integral ratio of the spectrum. In addition to the above, in the case of a copolymer containing styrene as another copolymer component, hydrogen of the aromatic ring of styrene is seen at 6.5 to 7.5 ppm, and the copolymer composition is similarly determined from the spectral ratio. Can be determined.

  The weight average particle diameter of the rubbery polymer is the sodium alginate method described in “Rubber Age, Vol. 88, p. 484-490 (1960), by E. Schmidt, PH B. Biddison”, that is, the concentration of sodium alginate. By using the fact that the diameter of the polybutadiene particles to be creamed differs depending on the particle size, it can be measured by a method of determining the particle size of 50% cumulative weight fraction from the weight proportion of cream and the cumulative weight fraction of sodium alginate concentration.

(9) Heat-resistant processing characteristics The following coating liquid for forming a hard coat layer was applied on a thermoplastic resin film by a three-coat reverse coat method so that the thickness after drying was 5 μm.

Dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd.): 90 parts by weight Macromonomer AN-6S (terminal group is methacryloyl group, high molecular weight component is styrene / acrylonitrile, number average molecular weight is 6,000 macro) Monomer) (Toagosei Co., Ltd., solid content 40% by weight): 25 parts by weight Photoinitiator 1-hydroxyphenyl ketone (Ciba Specialty Chemicals Co., Ltd.): 5 parts by weight Toluene: 50 parts by weight Methyl ethyl ketone: 50 parts by weight After coating, after two-step drying at 80 ° C. for 30 seconds and 100 ° C. for 30 seconds under a tension of 1.5 MPa in a floater oven, a high pressure having a strength of 80 W / cm installed at a height of 12 cm from the coating film The hard coat layer was formed by passing under a mercury lamp at a speed of 5 m / min. At this time, the state of the running film between the free rotating rolls / free rotating rolls (length between rolls 1 m, tension 1.5 MPa, transport speed 5 m / min) is observed immediately downstream of the ultraviolet irradiation by the high pressure mercury lamp lamp, The heat resistance workability was determined as follows.

  ◯: The flatness was good, and the flatness deterioration accompanied by the undulation with an amplitude of 20 mm or more and the curl on the edge of 10 mm or more did not occur.

  Δ: No deterioration in flatness accompanied by waviness with an amplitude of 20 mm or more occurred, but curling on the edge portion of 10 mm or more occurred.

  X: Film breakage occurred at a frequency of 1 time / 10 minutes or more, or flatness deterioration accompanied by waviness with an amplitude of 20 mm or more occurred.

  In addition, (triangle | delta) and (circle) are acceptable ranges.

(10) Winding characteristics With a commercially available menple type slitter, the roll is unwound at a winding tension of 100 N / m, a winding tension of 100 N / m, and a speed of 30 m / min. Was determined as follows.

  ○: The deviation of the end face of the roll is less than 1 mm, and there is no occurrence of acne-like air accumulation with a diameter of 1 mm or more on the roll surface.

  Δ: The deviation of the roll end face is 1 mm or more and less than 2 mm, and acne-like air pools having a diameter of 1 mm or more on the roll surface are 2 / roll or less.

  X: The deviation of the roll end face is 2 mm or more, or acne-like air pools having a diameter of 1 mm or more on the roll surface are 3 / roll or more.

  In addition, (triangle | delta) and (circle) are acceptable ranges.

[Example]
(1) Preparation of acrylic resin (A) Acrylic resin (A1)
Into a stainless steel autoclave with a capacity of 5 liters and equipped with a baffle and a foudra-type stirring blade, a methyl methacrylate / acrylamide copolymer suspension (prepared by the following method: 20 parts by weight of methyl methacrylate, 80 parts by weight of acrylamide) Then, 0.3 parts by weight of potassium persulfate and 1,500 parts by weight of ion-exchanged water are charged into the reactor and maintained at 70 ° C. while replacing the reactor with nitrogen gas. The resulting solution is obtained as an aqueous solution of methyl acrylate and acrylamide copolymer (using the obtained aqueous solution as a suspending agent), and a solution obtained by dissolving 0.05 part by weight in 165 parts by weight of ion-exchanged water is supplied. The mixture was stirred at 400 rpm and the system was replaced with nitrogen gas. Next, the following raw material monomer mixture was added while stirring the reaction system, and the temperature was raised to 70 ° C. The time when the internal temperature reached 70 ° C. was set as the start of polymerization, and kept for 180 minutes to complete the polymerization. Thereafter, the reaction system was cooled, the polymer was separated, washed, and dried in accordance with ordinary methods to obtain a bead-shaped copolymer intermediate (a-1). The polymerization rate of this copolymer (a-1) was 98%, and the weight average molecular weight was 100,000.

Methacrylic acid: 25 parts by weight Methyl methacrylate: 75 parts by weight t-dodecyl mercaptan: 1.5 parts by weight 2,2′-azobisisobutyronitrile: 0.4 parts by weight Additive (NaOCH ₃ ) is added thereto. Using a twin screw extruder (TEX30 (manufactured by Nippon Steel Co., Ltd., L / D = 44.5), while purging nitrogen from the hopper at an amount of 10 L / min, the screw rotation speed is 100 rpm, the raw material supply amount is 5 kg. / H, the intramolecular cyclization reaction was carried out at a cylinder temperature of 290 ° C. to obtain a pellet-shaped acrylic resin (A1), the composition ratio of methyl methacrylate units in this acrylic resin (A1) was 75 mol%, methacrylic acid units The composition ratio was 2 mol%, and the composition ratio of glutaric anhydride units was 23 mol%.

(B) Acrylic resin (A2-A6)
Acrylic resins (A2 to A6) were obtained in the same manner as in the previous period (A1) except that the mixing ratio of methacrylic acid and methyl methacrylate and the average molecular weight of the raw material monomer mixture were as shown in Table 1. The composition ratio of glutaric anhydride units in the obtained acrylic resin was as shown in Table 1.

(C) Acrylic resin (A7)
The mixing ratio of methacrylic acid and methyl methacrylate and the average molecular weight of the raw material monomer mixture are as shown in Table 1, and the acrylic resin (A7) was used in the same manner as in the previous period (A1) except that the intramolecular cyclization reaction was not performed. )

(2) Preparation of acrylic elastic particles (A) Acrylic elastic particles (B1)
In a glass container with a condenser (capacity 5 liters), charged with 120 parts by weight of deionized water, 0.5 parts by weight of potassium carbonate, 0.5 parts by weight of dioctyl sulfosuccinate, 0.005 parts by weight of potassium persulfate, and a nitrogen atmosphere After stirring under, 53 parts by weight of butyl acrylate, 17 parts by weight of styrene, and 2 parts by weight of allyl methacrylate (crosslinking agent) were charged. These mixtures were reacted at 70 ° C. for 30 minutes to obtain a core layer (inner layer) polymer. Next, a mixture of 21 parts by weight of methyl methacrylate, 9 parts by weight of methacrylic acid, and 0.005 parts by weight of potassium persulfate was continuously added over 90 minutes, and further maintained for 90 minutes to polymerize the shell layer (outer layer). The polymer latex was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered and dried to obtain acrylic elastic particles (B) having a two-layer structure (core-shell structure). The average particle diameter of the polymer particles measured with an electron microscope was 140 nm.

(B) Acrylic elastic particles (B2 to B4)
Acrylic elastic particles B2 to B4 were obtained in the same manner as in the previous period (B1) except that the composition of the raw material monomers and the average particle diameter were as shown in Table 2.

[Example 1]
80 parts by weight of the acrylic resin (A1) and acrylic elastic particles (B1) were blended at a composition ratio of 20 parts by weight, and a twin screw extruder (TEX30 (manufactured by Nippon Steel Co., Ltd., L / D = 44.5)) was used. Then, after kneading at a screw rotation speed of 150 rpm and a cylinder temperature of 280 ° C., foreign matter was filtered with a filter obtained by sintering and compressing stainless steel fibers having an average opening of 7 μm to obtain a pellet-shaped acrylic resin.

  Next, the pellets dried for 6 hours at 100 ° C. and 100 Pa were extruded with a vented 65 mm diameter single screw extruder at a vent pressure of 12 kPa and an extrusion set temperature of 260 ° C., and the resin was metered via a gear pump. went. Next, after filtering foreign matter through a filter obtained by sintering and compressing stainless steel fibers having an average opening of 7 μm, the mixture is extruded through a die (T die (lip gap 0.8 mm, set temperature 260 ° C.)) to obtain a surface temperature of 125 After cooling so that both sides are completely adhered to a cooling roll at 0 ° C, the film is gradually cooled through the cooling roll in the order of 90 ° C and 40 ° C, and both ends are removed with a shear cutter, and then wound into a roll. An unstretched acrylic resin film having a thickness of 40 μm was obtained. The average resin residence time from the extruder outlet to the T die outlet was 45 minutes and the draft ratio was 22.

  The characteristics of the obtained film are as shown in Table 4. The film had excellent heat resistance, optical isotropy, low internal haze, and excellent workability such as transportability and winding property.

[Example 2]
An unstretched acrylic resin film was obtained in the same manner as in Example 1 except that the raw material composition and film forming conditions used were as shown in Table 3. The characteristics of the obtained film are as shown in Table 4. The film had excellent heat resistance, optical isotropy, low internal haze, and excellent workability such as transportability and winding property.

[Example 3]
An unstretched acrylic resin film was obtained in the same manner as in Example 1 except that the raw material composition and film forming conditions used were as shown in Table 3. The properties of the obtained film are as shown in Table 4. The film had excellent heat resistance, optical isotropy, and excellent workability such as transportability and winding property. Moreover, although it was a little inferior in heat-resistant workability and the internal haze was a little high, it was in the range of the pass.

[Example 4]
An unstretched acrylic resin film was obtained in the same manner as in Example 1 except that the raw material composition and film forming conditions used were as shown in Table 3. The characteristics of the obtained film are as shown in Table 4. The film had excellent heat resistance, optical isotropy, low internal haze, and excellent workability such as transportability and winding property.

[Example 5]
An unstretched acrylic resin film was obtained in the same manner as in Example 1 except that the raw material composition and film forming conditions used were as shown in Table 3. The properties of the obtained film are as shown in Table 4. The film had excellent heat resistance, optical isotropy, and excellent workability such as transportability and winding property. Moreover, although the internal haze was somewhat high, it was within the acceptable range.

[Example 6]
An unstretched acrylic resin film was obtained in the same manner as in Example 1 except that the raw material composition and film forming conditions used were as shown in Table 3. The characteristics of the obtained film are as shown in Table 4. The film had excellent heat resistance, optical isotropy, low internal haze, and excellent workability such as transportability and winding property. Moreover, it was excellent in ultraviolet-absorbing ability and was particularly useful as a protective film for a polarizer.

[Comparative Example 1]
An unstretched acrylic resin film was obtained in the same manner as in Example 1 except that the raw material composition and film forming conditions used were as shown in Table 3. The characteristics of the obtained film are as shown in Table 4, and were inferior in workability such as transportability and winding property.

[Comparative Example 2]
An unstretched acrylic resin film was obtained in the same manner as in Example 1 except that the raw material composition and film forming conditions used were as shown in Table 3. The characteristics of the obtained film are as shown in Table 4, and were inferior in workability such as transportability and winding property.

[Comparative Example 3]
An unstretched acrylic resin film was obtained in the same manner as in Example 1 except that the raw material composition and film forming conditions used were as shown in Table 3. The characteristics of the obtained film are as shown in Table 4, and were inferior in heat resistance, optical isotropy, and transparency.

[Comparative Example 4]
An unstretched acrylic resin film was obtained in the same manner as in Example 1 except that the raw material composition and film forming conditions used were as shown in Table 3. The characteristics of the obtained film are as shown in Table 4, and the internal haze was high and the transparency was poor.

[Comparative Example 5]
An attempt was made to produce an unstretched acrylic resin film in the same manner as in Example 1 except that the raw material composition to be used and the film forming conditions were as shown in Table 3, but bubbles caused by the acrylic resin decomposition products were intermittently generated. However, a film could not be obtained.

[Comparative Example 6]
An unstretched acrylic resin film was obtained in the same manner as in Example 1 except that the raw material composition and film forming conditions used were as shown in Table 3. This unstretched acrylic resin film was stretched in the width direction using a uniaxial tenter at a stretching temperature of 100 ° C., a stretching ratio of 2.5 times, and a stretching speed of 7.2 m / min to obtain an acrylic resin film. The characteristics of the obtained film are as shown in Table 4 and were inferior in heat resistance, optical isotropy, and handleability.

  The film of the present invention is suitable for optical applications due to its excellent heat resistance and optical isotropy. Here, the optical application is a member for a display device, and particularly indicates a member used for a flat panel display such as a liquid crystal display, a plasma display, a field emission display, and an electroluminescence display. For example, plastic substrate, lens, polarizing plate, polarizing plate protective film, ultraviolet absorbing film, infrared absorbing film, electromagnetic wave shielding film, prism sheet, prism sheet substrate, Fresnel lens, optical disk substrate, optical disk substrate protective film, light guide plate, Examples include retardation films, light diffusion films, viewing angle widening films, reflection films, antireflection films, antiglare films, brightness enhancement films, prism sheets, and conductive films for touch panels. As useful.

Claims (12)

Including a thermoplastic resin having a glass transition temperature of 110 ° C. or higher, the total haze of the film is 1.6% or more, the internal haze is 1.0% or less, the in-plane retardation Δnd is 10 nm or less, and the thickness direction retardation Rth is A thermoplastic resin film of -10 to 10 nm. The thermoplastic resin film according to claim 1, wherein the surface haze is 1.0% or more. The thermoplastic resin film according to claim 1 or 2, wherein the thermoplastic resin is an acrylic resin. The thermoplastic resin film according to claim 3, wherein the acrylic resin is an acrylic resin (A) containing a glutaric anhydride unit represented by the following structural formula (1).

(In the above formula, R ¹ and R ² represent the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.) It is composed of 50 to 95% by mass of acrylic resin (A) containing a glutaric anhydride unit represented by the structural formula (1) and 5 to 50% by mass of acrylic elastic particles (B), and acrylic resin (A ) At least methyl methacrylate units 55 to 95 mol% and glutaric anhydride units 5 to 45 mol%, and the sum of methyl methacrylate units and glutaric anhydride units is 90 mol% or more. 4. The thermoplastic resin film according to 4. The thermoplastic resin film according to claim 5, wherein the acrylic elastic particles (B) have a weight average particle diameter of 50 to 300 nm. The acrylic elastic particles (B) are a polymer containing an acrylic resin whose inner layer contains an alkyl acrylate ester unit and / or an aromatic vinyl unit and whose outer layer contains a glutaric anhydride unit. The thermoplastic resin film according to claim 5 or 6, wherein the refractive index difference between the acrylic elastic particles (B) and the acrylic resin (A) is 0.010 or less. The thermoplastic resin film in any one of Claims 1-7 whose light transmittance in 380 nm is 10% or less. The thermoplastic resin film according to claim 1, which has a single-layer configuration. The thermoplastic resin film according to any one of claims 1 to 9, wherein a hard coat layer is laminated on at least one surface. The thermoplastic resin film according to any one of claims 1 to 10, which is used for optical applications. A method for producing a thermoplastic resin film in which a molten thermoplastic resin is extruded from a die onto a cooling roll using an extruder and solidified, and the draft ratio between the die and the cooling roll is set to 10 or more and is melted. The manufacturing method of the thermoplastic resin film in any one of Claims 1-11 which makes the average residence time from the extruder exit of a thermoplastic resin to a nozzle | cap | die exit 30-60 minutes.